Circuit interrupter



Nov. 3, 1931. G. BOSSARD C IRCUIT INTERRUPTER Filed June 4, 1950 Patented Nov. 3, 1931 UNITED STATES PATENT oFFlcE GIsBEnTLrossAnn, or DAYTON, omo, AssIGNon To GENERAL xoNTRoLAn cor:-

- rm, INc., or DAYTON, oIIIo, A CORPORATION or oHIo cIBcUIT INTEImIrITEnv Application med June 4,

This invention relates to mercury tube switches. l

One of the objects of the invention is the provision of a mercury tube switch having a novel arrangement of electrodes or conductive wires through which the electricity flows into or from the switch.

Another object of the invention is the provision of a mercury tube switch having upwardly and outwardly Haring wells or pockets receiving a quantity vof mercury, each well having a wire loop so that the mercury will be retained in the well lduring movements of the switch. y

Other objects and advantagesof the invention will be apparent from the following description, the appended claims, and the accompanying drawings, in which:

Fig. 1 is a side elevation of a mercury tube zo embodying the present invention;

Fig. 2 is a vertical sectional view through the tube; and

Fig.` 3 is an enlarged vertical section through one of the mercury wells.

The drawings show a preferred form of the. invention, the switch as an. entirety being designated generally by the numeral 10. This switch -contains a quantity of mercury or similar conductive liquid, as indicated at 80 11, the lswitch tube 12 being made of glass or the like. Preferably the space within the tube contains inert gas such as argon, or some other inert gas. it being understood that the mercury and the gas is sealed hermetically so that entrance of airand consequent oxidation of themercury is prevented.

As shown in Fig. 2 the glass tube is curved arcuately, and the convex side of the tube is provided with a series of depending wells or 40 pockets 14 each adapted to retain a' globule of mercury during normal switch movements. The mercury in the central well is adapted to be. connected -to a source of current and the two end wells are electrically lconnected to' suitable load circuits adapted 'to be alter- 1930. Serial No. 459,210.

towards one side and then the other, the

mercury bridging the space between the cen-l tral well and one of the end wells during such movement. e

Mercury tube switches have heretoforebeen constructed having depending well portions intended to hold globules of mercury so that the electrical circuit completed or broken by the switch will be made or broken between two portions of the mercury. Hereto'fore, however, these dependingwell portions have either l failed to satisfactorily retain the mercury globules during rapid movement of the switch or else these prior wells have been constricted at the point where they join the main body of the tube and under such conditions it has been found that a gas bubble will be formed in thetop of the well preventing electrical contact between the mercury in the main body of the switch and the mercury retained in the well. bubble will not permit the mercury in thev main body of the tube-to iow down to the small globule of mercury in the well rapidly enough for electrical contact to be completed, duringrapid movements of the tube; and if the constriction at the top of the well is not employed, in such prior constructions, then the mercury will not be retained in the well and the electrical circuit will be broken between the mercury and the electrode itself, with the resultant disintegration and deterioration of the electrode.

In accordance with the present invention each well 14 increases indiameter upwardly towards the tube body. This upward increase in diameter is rather gradual, but the upper Send of the well is of substantiallyr larger size. than an intermediate portion so that a gas bubble will not be formed between Curiously enough this j the mercury in the lower portion of the v hard glass the electrode is preferably prevent4 any, even instantaneous, formation of va as bubble and consequently the main body o the mercury in the tube can immediately make contact with the globule of mercury in the well during rapid switch movements.

In order to retain a globule of mercury in the well when the switch tilts and the main body of the mercury fiows towards the other side of the switch, the electrodes through which the electricity flows `into or from the switch extend fairly well into the well-and are provided with re-entrant portions providing a loop which serves to hold the mercury -from being thrown out of the well, even during rapid movements, and in spite of the upward flare of the well. The mercury seems to cling to this loop rather tenaciously and some quantity of mercury will therefore al ways remain in the well during normal l switch movements and the electrical circuitwill always be broken between diii'erent portions o the mercury.

The electrode or electrical conductor through which the current flows from the switch is shown more in detail in Fig. 3, which is representative of any of the plurality of wells of the tube. This electrode preferably comprises a single integral wire 18 reversely ben* at 19 and 20 to provide the adjacent parallel wire portions 21, 22 and 23. The spacing between these wire portions is such that they may each besurrounded entirely by glass where they extend through the well from the exterior. The wire electrode, which is preferably rather rigid, may be of a suitable nickel iron -alloy having a platinum sheathing, and having a diameter of about .55 millimeters, orplatinum of about .35 to .55 millimeters diameter dependingr upon the current value, or tungsten sheathed in glass, as -well asia number of other materials having a coeilicient of expansion of the same order as that `of the glass employed. When using platinum with soft glass such as lead glass, or using tungsten with pyrex or joined to the glass of the tube body by a special glass having a'coelicient of expansion `between that of the glass of thel tube body and that of the electrode and which makes a satisfactory seal with both of those parts. A small portion of this special glass is applied to the electrode, and then the special glass is welded at 16 to the main body of glass forming the tube and the well.

The number of spaced wire portions 21, 22 and 23 of each of the electrodes is dependent upon the total current to be carried by the electrode. If the current is large then quite a number of these wire portions are provided by reversely looping an electrode wire a number of times, thus providing several loops within the well. Regardless of how many such wire portions there are in the elect-rode, the various projecting parts of thesewires are bound together and both physically and electrically connected to the terminal wire 25, which is preferably coiled around the projecting parts of the electrode as indicated in Fig. 3, and then soldered or otherwise permanently connected electrically `to the electrode at a point immediately adj acent the outer portlons of the well. The electrodes may be easily formed and handled as the wire is heavy enough -to maintain its form and is thus readily handled. As the wire of the entire electrode is a single integral piece, continuity of electrical contact is insured, even should one of the portions be inadequately joined to the terminal wire 25.

Each of the wells 14 is preferably incased in a metal cap 27 which is connected by suitable cement Or plaster of Paris 28 to its well. Preferably the insulation 29 of the terminal Wire 25 stops adjacent the lower end of this metal sheath. The terminal wires 25 are of suitable length so that the tube may readily be connected to other electrical conductors in any suitable manner.

It will now be apparent that should the tube be rocked down towards the left from its position shown in Fig. 2, the main body of mercury within the tube will contact with the mercury globule 30 in the left end well 14. An electrical contact will then be made from the middle wire terminal through the mercury to the left-hand wire terminal and so on'.to the load connected therewith. When the tube is then rocked down toward the right the main body of mercury in the tube will separate at the globule 30, the break of the current taking place between the two mercury portions and well above the electrode in the lefthand well. Even though the movement of the tube is rapid, the globule of mercury 30 will be retained in the lefthand well 14 on account of the reluctance of this globule of mercury to separate from the loo l19, and also from the upstanding wire end 21, these portions projecting sulhciently far up into the' well that they provide the necessary resistance to the mercury, without, however, being of undue length and preferably remaining well below the top of the globule of mercury which it retains.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without depart-ing from the scope of the invention which is defined in' the appended claims.

What is claimed is:

1. A mercury tube switch comprising a sealed `glass container tube containing a quantity of mercury, said tube having a well the sides of which extend upwardly and adjoin the main body of the tube, and a conductive.

well and having re-entrant portions providing a loop within the wellfor retaining mercury therein during switch operations.

2. A mercury `tube switch comprising a sealed glass container tube containing a quantity of mercury, said tube having a well extendinfr downwardly from the main body of the tube, the sides of the well flaring outwardly and upwardly to the adjoining portion of the main body of the tube, and a con- -ductive wire4 projecting from the exterior into said well and having re-entrant portions providing a loop within the well for retain- 4ing mercury therein during switch opera- A stantially parallel wire tions.

3'. A vmercury tube switch comprising a sealed glass container tube containing a quantity of mercury, said tube having a well extending downwardly from the main body of the tube, a conductive wire projecting from the exterior into said well and providing a loop within the well for retaining mercury during switch operations, and a sepanature.

` GISBERT L. BOSSARD.

rate terminal-wire physically and electrically connected in a permanent manner to the ex- `teriorly projecting portions of said conductive'wire directly adjacent `the outside of said well.

4.. A mercurytube switch comprising a sealed glass container tube containing a quantity of mercury, said tube having a well extending downwardly therefrom, and a reversely bent conductor having spaced subortions extending from the exterior into sald well and providing 'afloop Within the well for retaining mer-` cury during switch operations, the glass of the main body of the tube having a coefficient of expansion differingl from the coefficient of expansion of the conductor,` and the glass immediately adjacent the conductor having a coefficient of'expansion between the coeiicient of expansion of the electrode and the glass .of

the main body ofthe tube.

5. Agrmercury tube. -switch comprising' a ysealed container tube containing a quantity of mercury, said tube having a Well eXtending downwardly therefrom, the sides of the vwell flaring outwardly and upwardly to the adjoining' portion of the main body-.of the tube,'an integral reversely bent conductor having spaced substantially parallel wire portions extending from the exterior into said well and providing a loop within the well for retainingmercury during switch operations,

- anda terminal wire connected to the exteriorly projecting parts of said wire portions adjacent the outside of said well.

6. A mercury tube switch j comprising a curved tubecontaining a quantity of mercury sealed therein, said tube having a plurality of spaced wells extending downwardly from the convex side'of the tube, the sides of the wells-flaring outwardly and upwardly to the adjoining portions of the main body` 

